High-voltage earthing switch

ABSTRACT

A high-voltage earthing switch is disclosed. A static contact of the earthing switch is connected with the first end of a conductive copper busbar. The second end of the conductive copper busbar is connected with a transformer. The conductive copper busbar includes a first segment and a second segment connected with the first segment. The first segment is one straight segment and an end is taken as an end the first end of the conductive copper busbar. The first segment is parallel to the instantaneous action direction of the moving contact when a moving contact engages the static contact. The first segment extends from the static contact in the direction opposite to the instantaneous action direction of the moving contact when the moving contact engages the static contact. The second segment is connected with the other end of the first segment, and extends towards the side of the first segment facing away from the moving contact. The second segment is located at one side of an extended line of one end of the contacting finger connected with the moving contact when the earthing switch switching-on in the direction opposite to the instantaneous action direction at the moment when the moving contact engages the static contact. An electromotive force between the conductive copper busbar and the contacting finger of the earthing switch of the invention may have a positive effect on a switching-on.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation of international PCT applicationserial no. PCT/CN2016/086648, filed on Jun. 22, 2016, which claims thepriority benefit of China application no. 201510530437.0, filed on Aug.26, 2015. The entirety of each of the above-mentioned patentapplications is hereby incorporated by reference herein and made a partof this specification.

BACKGROUND Technical Field of the Present Invention

The present invention belongs to the field of electrical technology andrelates to an earthing switch generally used in an electrical cabinet,and more particular to a high-voltage earthing switch.

Technical Background of the Present Invention

The arrangement of a conductive copper busbar of a earthing switch inthe prior art is determined according to a use occasion, the effect ofan electromotive force between the conductive copper busbar and acontacting finger obtained at the moment of engaging on a switching-onaction is neglected, when the electromotive force between the conductivecopper busbar and the contacting finger produces a negative effect onthe switching-on action, the resistance of the earthing switch to theswitching-on is caused to be increased, in order that the reliability ofthe switching-on is ensured, the strength of a spring has to beincreased, the consequence thereof not only results in an increasedmaterial cost, but also makes a moving contact, a static contact andother related components suffer from a greater impact in theswitching-on, further resulting in a shortened service life of theearthing switch.

In addition, in a switching-on state, the contact area between themoving contact and the static contact is an important factor affectingthe electrical performance of the earthing switch. A flat clampingstructure has been provided between the moving contact and the staticcontact of the traditional earthing switch. For example, a staticcontact with a better performance in the current market comprises abase, two contacting plates opposite to each other are provided on thebase, the two contacting plates are perpendicular to the upper face ofthe base, the outer sides of the two contacting plates are respectivelyprovided with a supporting plate of which the lower part is relativelyfixed with the base, two sets of belleville springs coaxially stackedare provided between the upper part of each supporting plate and thecontacting plate at the same side. A contact surface between thecontacting plate of the above static contact and a blade of the movingcontact is in a shape of an oval of which two close ends are narrow andof which two remote ends are wide, or in a shape of a pillow of whichtwo ends are wide and of which the middle is narrow. By setting two setsof the belleville springs on one side, the contact surface between thecontacting plate of the static plate and the blade of the moving contactis increased. The design further effectively improves the holdingcapacity between the contacting plate and the blade of the movingcontact, and further improves the service life of a product under thepremise of ensuring the connection performance of the static contact.However, with this design, the contact area between the static contactand the moving contact is still limited.

SUMMARY OF THE PRESENT INVENTION

The purpose of the present invention is to overcome the deficiencies ofthe prior art and to provide a new earthing switch, the earthing switchuses an arrangement manner of a new contact and a conductive copperbusbar which may improve the mechanical and electrical performance ofthe switch.

An earthing switch comprises a moving contact, a contacting finger, aspring, a rack, a static contact, a conductive copper busbar and atransformer. The moving contact is fixedly connected with the contactingfinger, the contacting finger is swingably connected with the rack, thespring is connected between the contacting finger and the rack. thestatic contact is fixedly connected with the rack via an insulator, thestatic contact is connected with the first end of the conductive copperbusbar, the second end of the conductive copper busbar is connected withthe transformer, wherein, the conductive copper busbar at leastcomprises a first segment and a second segment connected with the firstsegment, the first segment is one straight segment and an end of thefirst segment is taken as the first end of the conductive copper busbar,the first segment is parallel to the instantaneous action direction ofthe moving contact when the moving contact engages the static contact,and the first segment extends from the static contact in the directionopposite to the instantaneous action direction of the moving contactwhen the moving contact engages the static contact, the second segmentis connected with the other end of the first segment, the second segmentextends towards the side of the first segment facing away from themoving contact, the second segment is located at the side of an extendedline of one end of the contacting finger connected with the movingcontact when the earthing switch switching-on in the direction oppositeto the instantaneous action direction at the moment when the movingcontact engages the static contact.

Furthermore, the second segment comprises a straight segment, thestraight segment of the second segment is perpendicular to the firstsegment.

Furthermore, the second segment consists of two straight segments,wherein the first straight segment is connected with the first segment,the second straight segment is connected with the first straightsegment, the second straight segment is perpendicular to the firstsegment, an angle between the first straight segment and the firstsegment is an obtuse angle, an angle between the first straight segmentand the second straight segment is an obtuse angle.

Based on the above structural design of the conductive copper busbar,the electromotive force between the conductive copper busbar and thecontacting finger may positively affect the connection between themoving contact and the static contact at the moment when the movingcontact of the earthing switch is connected with the static contactthereof.

Furthermore, the contacting finger consists of a front end portionfixing the moving contact and a swing atm connecting the front endportion and the rack, a ladder is formed between the front end portionof the contacting finger and the second straight segment of the secondsegment of the conductive copper busbar, two diagonals of the ladder ared1 and d2 respectively, two waists thereof are s1 and s2 respectively,the height thereof is a, preferably, the proportion of d1:d2:s1:s2:a is1:2.2:1.22:1.61:1, the front end portion of the contacting finger andthe first segment of the conductive copper busbar (excluding the portioncontacted with the static contact, and the remaining portion is aneffective portion) constitute two conductors perpendicular to eachother, the length of the front end portion of the contacting finger isset as a, the length of the effective portion of the first segment ofthe conductive copper busbar is set as h, the widths of the front endportion of the contacting finger and the first segment of the conductivecopper busbar are both 2 r, preferably, the proportion of a:h:r is7.53:6.08:1.

Furthermore, the moving contact is a circular moving contact, the staticcontact comprises a body and a plurality of contacting finger stripsprovided in a circular hole on the body, the contacting finger strip isarranged in a circular array along the side wall of the circular hole. aleaf spring is provided between the contacting finger strip and the sidewall of the circular hole, preferably, a total of 16 and abovecontacting finger strips are provided. A plurality of the contactingfingers is in a ring-shaped arrangement, being capable of effectivelyincreasing a contact area, reducing a contact resistance, and preventingthe contact from welding.

Furthermore, the static contact is fixed to the insulator through anL-shaped right-angle connector. One surface of the body of the staticcontact which is provided with a circular hole is set as the topsurface, the other surface opposite to the top surface is the bottomsurface of the body, and the remaining surfaces are the side surfaces ofthe body. One side of the side surface of the body of the static contactis a plane, the first end of the conductive copper busbar is fixedlyconnected to the plane, the side thereof opposite to the plane is an arcsurface, the arc surface has a smooth transition with each the other twosides of the side surfaces of the body of the static contact. Oneright-angle edge of the L-shaped right-angle connector is fixedlyconnected with the end surface of the insulator, the other right-angleedge of the L-shaped right-angle connector is fixedly connected with thebottom surface of the body of the static contact. The structure of thebody of the above static contact may achieve the technical effects thatthe switch is reliably switched on and off and the assembly thereof isconvenient, under the premise of ensuring that the technical solutionproposed by the present invention for making an electromotive force playa positive effect may be realized.

Furthermore, a gap of 2.5 mm to 5.5 mm is provided between theneighboring contacting finger strips of the static contact, since thegap is provided, when current flows by, a holding effect based on theelectromotive force may be formed, increasing a contact pressure betweenthe contacting finger strip and the moving contact.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram of an overall structure of a earthing switch of thepresent invention.

FIG. 2 is a top view of a static contact.

FIG. 3 is a structural diagram of a single contacting finger of a staticcontact and a reed of an earthing switch.

FIG. 4 is a diagram of an engagement state of a moving contact and acontacting finger strip.

FIG. 5 is an analysis diagram of an electromotive force of an earthingswitch.

FIG. 6 is an analysis diagram of an electromotive force between a frontend portion of a contacting finger and a second straight segment of asecond segment of a conductive copper busbar.

FIG. 7 is an analysis diagram of an electromotive force between a frontend portion of a contacting finger and a first segment of a conductivecopper busbar.

In the Figs.: Moving Contact 1, Contacting Finger 2, Spring 3, Rack 4,Insulator 6, Static Contact 7, Conductive Copper Busbar 8, Transformer9, Leaf spring 10, L-shaped right-angle connector 11, First segment ofthe conductive copper busbar 81, Second segment of the conductive copperbusbar 82, First straight segment of the second segment of theconductive copper busbar 821, Second straight segment of the secondsegment of the conductive copper busbar 822, instantaneous actiondirection of the moving contact when the moving contact engages thestatic contact 12, extended line of one end of the contacting fingerconnected with the moving contact when the earthing switch switching-on13, Contacting finger strip 14.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

As shown in FIGS. 1-4, an earthing switch of the invention comprises amoving contact 1, a contacting finger 2, a spring 3, a rack 4, aninsulator 6, a static contact 7, a conductive copper busbar 8, and atransformer 9. The moving contact 1 is fixedly connected with thecontacting finger 2. The contacting finger 2 is connected with the rack4. The spring 3 is connected between the contacting finger 2 and therack 4. One end of the insulator 6 is fixed with the rack 4. The staticcontact 7 is fixed on the other end of the insulator 6 via an L-shapedright-angle connector 11. The first end of the conductive copper busbar8 is fixed with the static contact 7, and a second end of the conductivecopper busbar 8 is connected with the transformer 9.

In the following description, as shown in FIG. 1, the instantaneousaction direction 12 of the moving contact when the moving contactengages the static contact is downward, otherwise, being upward, thedirection indicated by one end of the contacting finger connected withthe moving contact in the engaged state is taken as the right,otherwise, as the left.

The conductive copper busbar comprises a first segment 81 with an endtaking as the first end of the conductive copper busbar and a secondsegment connected with the first segment 81, the first segment 81 isparallel to the instantaneous action direction 12 of the moving contactwhen the moving contact engages the static contact, the first segment 81extends upward from the static contact 7; the second segment extendstoward right side from the upper end of the first segment 81, the secondsegment is located above an extended line 13 of the contacting fingertoward the right side in the switching-on state. the second segmentconsists of two straight segments, wherein the left end of the firststraight segment 821 is connected with the upper end of the firstsegment 81, the second straight segment 822 is connected with the rightend of the first straight segment 821, the second straight segment 822is perpendicular to the first segment 81, the angle between the firststraight segment 821 and the first segment 81 is an obtuse angle, theangle between the first straight segment 821 and the second straightsegment 822 is also an obtuse angle.

A circular hole is provided on the body of the static contact 7, 16contacting finger strips 14 are arranged in a circular array along theside wall of the circular hole in the circular hole, a gap of 2.5 mm to5.5 mm is provided between the respective contacting finger strips 14 ofthe static contact. A leaf spring 10 is provided between the contactingfinger strip 14 and the side wall of the circular hole.

The right side surface of the body of the static contact is one plane,and the first end of the conductive copper busbar 8 is fixedly connectedto the plane. The left side surface of the body of the static contact 7is an arc surface, and the arc surface has a smooth transition withfront and back side surfaces of the body of the static contact 7. Thevertical edge of the L-shaped right-angle connector 11 is fixed with theend surface of the insulator 6 via a bolt, and the horizontal edge ofthe L-shaped right-angle connector 11 is fixed with the bottom surfaceof the body of the static contact 7 via the bolt.

The contacting finger 2 consists of a front end portion fixing themoving contact and a swing arm connecting the front end portion and therack 4.

As shown in FIGS. 5-7, a ladder is formed between the front end portionof the contacting finger and the second straight segment of the secondsegment of the conductive copper busbar. Two diagonals of the ladder ared1 and d2, respectively. Two waists thereof are s1 and s2, respectively.The height thereof is a. Preferably, the proportion of d1:d2:s1:s2:a is1:2.2:1.22:1.61:1. The front end portion of the contacting finger andthe first segment of the conductive copper busbar (excluding the portioncontacted with the static contact, and the remaining portion is aneffective portion) constitute two conductors perpendicular to eachother. The length of the front end portion of the contacting finger isset as a. The length of the effective portion of the first segment ofthe conductive copper busbar is set as h. The widths of the front endportion of the contacting finger and the first segment of the conductivecopper busbar are both 2 r. Preferably, the proportion of a:h:r is7.53:6.08:1.

An electromotive force loop coefficient between the front end portion ofthe contacting finger and the second straight segment of the secondsegment of the conductive copper busbar is formulated as:

$c = {\frac{\left( {d_{1} + d_{2}} \right) - \left( {s_{2} + s_{1}} \right)}{a}.}$

An electromotive force loop coefficient between the front end portion ofthe contacting finger and the first segment of the conductive copperbusbar is formulated as:

$c = {{\ln \left\lbrack \frac{2{ah}}{r\left( {h + \sqrt{\left. {h^{2} + a^{2}} \right)}} \right.} \right\rbrack}.}$

Therefore, distance between two wires a is increased would effectivelyreduce the coefficient of the electromotive force c, and thus being ableto reduce the interference of the electromotive force on the earthingswitch.

The process of an action of the earthing switch is provided as follows.When it is needed to switch on, an operational mechanism drives thecontacting finger to be rotated clockwise. When the contacting finger isrotated by a critical point of the spring, the contacting finger isrotated rapidly until the contacting finger is rotated clockwise by 90°,then the moving contact is inserted into the contacting finger strip ofthe earthing static contact, and the moving contact engages the staticcontact to realize the earthing. When it is needed to switch off, theoperational mechanism drives the contacting finger to be rotatedcounterclockwise. The moving contact disengages from the static contact.When the contacting finger is rotated by a critical point of the spring,the contacting finger is rotated rapidly until the contacting finger isrotated counterclockwise by 90°, then the contacting finger keeps a setposition under a limit position.

What is claimed is:
 1. A high-voltage earthing switch, comprising amoving contact, a contacting finger, a rack, an insulator, a staticcontact, a conductive copper busbar, and a transformer; wherein themoving contact is fixedly connected with the contacting finger, thecontacting finger is swingably connected with the rack, the staticcontact is fixedly connected with the rack via the insulator, the staticcontact is connected with a first end of the conductive copper busbar, asecond end of the conductive copper busbar is connected with thetransformer, the conductive copper busbar comprises a first segment anda second segment connected with the first segment, the first segment isone straight segment, an end of the first segment is the first end ofthe conductive copper busbar, the first segment is parallel to aninstantaneous action direction of the moving contact when the movingcontact engages the static contact, the first segment extends from thestatic contact in a direction opposite to the instantaneous actiondirection of the moving contact when the moving contact engages thestatic contact, the second segment is connected with the other end ofthe first segment, the second segment extends towards a side of thefirst segment, which faces away from the moving contact, and the secondsegment is located at one side of an extended line of one end of thecontacting finger connected with the moving contact when the earthingswitch switching-on in the direction opposite to the instantaneousaction direction of the moving contact when the moving contact engagesthe static contact.
 2. The high-voltage earthing switch according toclaim 1, wherein the second segment comprises a straight segment, andthe straight segment of the second segment is perpendicular to the firstsegment.
 3. The high-voltage earthing switch according to claim 1,wherein the second segment consists a first straight segment and asecond straight segment, the first straight segment is connected withthe first segment, the second straight segment is connected with thefirst straight segment, the second straight segment is perpendicular tothe first segment, an angle between the first straight segment and thefirst segment is an obtuse angle, and an angle between the firststraight segment and the second straight segment is an obtuse angle. 4.The high-voltage earthing switch according to claim 1, wherein themoving contact is a circular moving contact, the static contactcomprises a body and a plurality of contacting finger strips provided ina circular hole on the body, the plurality of contacting finger stripsare arranged in a circular array along the side wall of the circularhole, and a leaf spring is provided between the contacting finger stripand the side wall of the circular hole.
 5. The high-voltage earthingswitch according to claim 4, wherein the static contact is fixed to theinsulator through an L-shaped right-angle connector, the body of thestatic contact comprises four side surfaces, one of the four sidesurfaces of the body of the static contact is a plane, the first end ofthe conductive copper busbar is fixedly connected to the plane, the sidesurface opposite to the plane is an arc surface, the arc surface has asmooth transition with each of the other two of the four side surfacesof the body of the static contact, one right-angle edge of the L-shapedright-angle connector is fixedly connected with an end surface of theinsulator, the other right-angle edge of the L-shaped right-angleconnector is fixedly connected with a bottom surface of the body of thestatic contact.
 6. The high-voltage earthing switch according to claim5, wherein a gap of 2.5 mm to 5.5 mm is provided between the neighboringcontacting finger strips of the static contact.